Issue 9, 2008

Molecular dynamics simulation of the mesophase behaviour of a model bolaamphiphilic liquid crystal with a lateral flexible chain

Abstract

We present simulations of a coarse-grained model of a bolaamphiphile liquid crystal molecule with a grafted flexible side chain. The coarse-graining approach employed is based on minimising the attractions present in the system, on the premise that the most important features of the liquid structure stem from the balance between the close range repulsions and the strong directional forces typical of hydrogen bonding and association. The model consists of six fused rigid spheres, where the two end spheres have a significant attraction amongst themselves while the rest are repulsive in nature. A weakly self-attracting lateral chain consisting of fully flexible tangently bonded spheres is attached to one of the central spheres. A parametric study is made of the configurations of collectives of these molecules at temperatures that span from the isotropic fluid range down to the onset of crystallisation. The underlying rigid core molecules (with no side chain) are set up to exhibit a smectic liquid crystal behaviour. Upon increasing the number of spheres in the lateral chains from 1 to 12, the liquid regions exhibit a rich variety of self-assembled structures; for small number of lateral chain spheres columnar arrays of different cross sections (triangular, square, rectangular, hexagonal) are obtained and for the longer chains lamellar structures of different interlayer spacing are observed. We showcase and give a rational physical explanation for the global phase behaviour of the model, based on pertinent order parameters and apparent diffusivities of the several regimes encountered. Although no attempt has been made to fit the parameters of the model to real molecules, the model is inspired by the reported synthesis of a family of T-shaped polyphilic molecules (C. Tschierske, Chem. Soc. Rev., 2007, 36, 1930–1970) where some of the above mentioned phases have been inferred from experimental measurements.

Graphical abstract: Molecular dynamics simulation of the mesophase behaviour of a model bolaamphiphilic liquid crystal with a lateral flexible chain

Supplementary files

Article information

Article type
Paper
Submitted
25 Feb 2008
Accepted
14 May 2008
First published
24 Jun 2008

Soft Matter, 2008,4, 1820-1829

Molecular dynamics simulation of the mesophase behaviour of a model bolaamphiphilic liquid crystal with a lateral flexible chain

A. J. Crane, F. J. Martínez-Veracoechea, F. A. Escobedo and E. A. Müller, Soft Matter, 2008, 4, 1820 DOI: 10.1039/B802452A

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements